CN115089380A

CN115089380A - Absorbent article comprising nonwoven fabric sheet for absorbent, and method for producing nonwoven fabric sheet used in absorbent article

Info

Publication number: CN115089380A
Application number: CN202210749974.4A
Authority: CN
Inventors: 木村明宽; 出谷耕; 丹下悟; 松村纪明; 野口贵司
Original assignee: Unicharm Corp
Current assignee: Unicharm Corp
Priority date: 2014-05-12
Filing date: 2015-02-03
Publication date: 2022-09-23
Also published as: WO2015174106A1; KR20190071841A; EP3143976A4; EP3143976A1; AU2015260605B2; JP6411066B2; JP2015213643A; KR20170005809A; KR102079504B1; US20170079856A1; KR102252288B1; CN106456402A; AU2015260605A1; MY177396A

Abstract

The present invention provides an absorbent article including a nonwoven fabric sheet for an absorbent having excellent liquid diffusibility, without using a strength-imparting means such as subsequent application of a binder which may inhibit liquid diffusibility, and a method for producing the nonwoven fabric sheet used in the absorbent article. An absorbent article (1) of the present invention comprises a liquid-permeable front sheet (2), a liquid-impermeable back sheet (3), an absorbent body (4) positioned between the front sheet (2) and the back sheet (3), and a nonwoven fabric sheet (8) for the absorbent body (4), wherein the nonwoven fabric sheet (8) comprises: a pulp fiber layer (81) containing pulp and having a first side and a second side; a first surface-side fiber layer (82) which is arranged on the first surface side of the pulp fiber layer (81) and mainly comprises hydrophilic fibers having an average fiber length of 25mm to 64 mm; and a second surface-side fiber layer (83) which is disposed on the second surface side of the pulp fiber layer (81) and mainly comprises hydrophilic fibers having an average fiber length of 25mm to 64 mm.

Description

Absorbent article comprising nonwoven fabric sheet for absorbent, and method for producing nonwoven fabric sheet used for absorbent article

This application is filed as a divisional application entitled "absorbent article comprising nonwoven fabric sheet for absorbent article and method for producing nonwoven fabric sheet used in the absorbent article" filed on 3/2/2015 and having application number 201580024906.

Technical Field

The present invention relates to an absorbent article including a nonwoven fabric sheet for an absorbent, and a method for manufacturing the nonwoven fabric sheet used in the absorbent article.

Background

Absorbent articles such as disposable diapers, sanitary napkins and panty liners are generally composed of a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body disposed between the top sheet and the back sheet, and particularly, a core of superabsorbent polymer particles covering the inside of the absorbent body is required to reliably hold the superabsorbent polymer particles both in dry and wet states, and further, a function of rapidly diffusing body fluid such as urine or blood that has reached the absorbent article to a wide range of the absorbent body and rapidly absorbing the body fluid by the superabsorbent polymer particles is required.

For example, patent document 1 discloses an absorbent article having a substantially longitudinal length and including a liquid-permeable surface material, a liquid-retentive absorbent member, and a liquid-impermeable leakproof material, wherein the absorbent member includes a diffusible absorbent sheet and an absorbent-retentive sheet located on the back side of the diffusible absorbent sheet, and (a) the diffusible absorbent sheet has a hydrophilicity (cos θ) of 0.5 to 1 and a gram water absorption rate in the longitudinal direction of 40[ mm/min ]]The above sheet, wherein (b) the absorption-retention sheet has a capillary osmotic pressure of 4000 to 15000[ dyn/cm ² ]The sheet comprising the fiber assembly of (1) has an absorption amount of physiological saline of 40 to 70 g/g]And the absorption rate was 2[ ml/0.3g polymer/min]The super absorbent polymer is a laminate sheet having 10 to 100 wt% of the fiber aggregate sandwiched therebetween (see claim 1).

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 4-89053

Disclosure of Invention

Problems to be solved by the invention

In the absorbent article disclosed in patent document 1, the diffusible absorbent sheet of the absorbent body is formed by bonding the fibers using polyvinyl alcohol or the like as a binder or by thermally bonding the fibers by a spunbond method in order to maintain the strength thereof, and therefore, the liquid diffusibility may be inhibited by the bonded portion or the thermally bonded portion.

Accordingly, an object of the present invention is to provide an absorbent article including a nonwoven fabric sheet for an absorbent having excellent liquid diffusibility without using a strength-imparting means such as subsequent application of an adhesive that may inhibit liquid diffusibility, and a method for producing the nonwoven fabric sheet for an absorbent used in the absorbent article.

Means for solving the problems

An absorbent article of the present invention includes a liquid-permeable front sheet, a liquid-impermeable back sheet, an absorbent body positioned between the front sheet and the back sheet, and a nonwoven fabric sheet for the absorbent body, wherein the nonwoven fabric sheet includes: a pulp fiber layer comprising pulp and having a first face and a second face; a first surface-side fiber layer which is disposed on the first surface side of the pulp fiber layer and mainly contains hydrophilic fibers having an average fiber length of 25mm to 64 mm; and a second surface-side fiber layer which is disposed on the second surface side of the pulp fiber layer and mainly comprises hydrophilic fibers having an average fiber length of 25mm to 64 mm.

According to the absorbent article of the present invention, the nonwoven fabric sheet for an absorbent comprising 3 or more layers including the pulp fiber layer, the first surface side fiber layer and the second surface side fiber layer is formed by interlacing fibers with each other by a high-pressure water flow without using a strength-imparting means such as a subsequent application of a binder which may inhibit liquid diffusibility, and therefore, liquid such as body fluid can be widely and rapidly diffused in the surface direction of the nonwoven fabric sheet by utilizing the capillary phenomenon of the fiber aggregate forming the first surface side fiber layer and the second surface side fiber layer. Further, since the first surface-side fiber layer and the second surface-side fiber layer are disposed on both surfaces of the pulp fiber layer, the liquid diffused in the surface direction in the first surface-side fiber layer and the second surface-side fiber layer can be absorbed from both surfaces of the pulp fiber layer, the water retention amount of the nonwoven fabric sheet can be greatly increased, and the liquid diffusion in the surface direction of the nonwoven fabric sheet can be continuously achieved.

Effects of the invention

According to the present invention, an absorbent article including a nonwoven fabric sheet for an absorbent having excellent liquid diffusibility and a method for producing a nonwoven fabric sheet for an absorbent used in the absorbent article can be provided.

Drawings

Fig. 1 is a perspective view (schematic view) of a disposable diaper according to an embodiment of the absorbent article of the present invention.

Fig. 2 is a plan view of the disposable diaper of fig. 1 in an unfolded state.

Fig. 3 is a cross-sectional view taken along the width direction of line III-III' of fig. 2.

Fig. 4 is a cross-sectional view (schematic view) of a nonwoven fabric sheet according to an embodiment of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the absorbent article of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a perspective view (schematic view) of a disposable diaper according to an embodiment of the absorbent article of the present invention, and fig. 2 is a plan view of the disposable diaper of fig. 1 in an unfolded state. As shown in fig. 1 and 2, a disposable diaper 1 according to an embodiment of the present invention includes: a front portion 11 contacting the abdomen of the wearer, a middle portion 12 contacting the crotch of the wearer, and a rear portion 13 contacting the buttocks and/or the back of the wearer. As shown in fig. 1, the joining

portions

14a and 14b join the

side portions

111a and 111b of the front panel portion 11 and the

side portions

131a and 131b of the rear panel portion 13 to each other, so that a waist opening is formed by the end portion 112 of the front panel portion 11 and the end portion 132 of the rear panel portion 13, and a leg opening is formed by the

side portions

121a and 121b of the intermediate portion 12, whereby the disposable diaper 1 has a pants-type shape.

As shown in fig. 1 and 2, the disposable diaper 1 includes: a surface sheet 2 made of a liquid-permeable nonwoven fabric sheet, plastic film, or the like; a back sheet 3 made of a liquid-impermeable polyethylene film or the like; an absorbent body 4 disposed between the front sheet 2 and the back sheet 3; a liquid-impermeable cover sheet 5; and

elastic members

61, 62, 63, 64. The cover sheet 5 provided on the skin surface side surface of the topsheet 2 has an opening 51 formed substantially at the center, and a part of the topsheet 2 (a part of the region where the absorbent member 4 is disposed) is exposed from the opening 51 of the cover sheet 5, and forms the skin surface side surface of the disposable diaper 1 together with the cover sheet 5.

As shown in fig. 1 and 2,

elastic members

61, 62, 63, 64 are provided between the back sheet 3 and the cover sheet 5 having an hourglass shape of substantially the same size. A waistline gather is formed at the waistline opening by the elastic contractive force of the

elastic members

61, 62, and a leg gather (cuff) on the leg side) is formed at the leg hole opening by the elastic contractive force of the

elastic members

63, 64. The leg gathers can prevent leakage of excrement from the leg openings. In the present specification, the width direction X refers to a width direction (short-side direction) in a plan view of the disposable diaper 1 (absorbent article) in an unfolded state, and the length direction Y refers to a length direction (front-back direction of a wearer) in a plan view of the disposable diaper 1 (absorbent article) in an unfolded state, and the width direction X and the length direction Y are orthogonal to each other in a plan view.

Hereinafter, an absorbent body used in a disposable diaper (absorbent article) according to an embodiment of the present invention and a nonwoven fabric sheet for the absorbent body will be described in detail. Fig. 3 is a cross-sectional view in the width direction along the line III-III' of fig. 2. As shown in fig. 3, the absorbent body 4 of the present embodiment includes: an absorbent core 7 made of a water-absorbent material, a nonwoven fabric sheet 8 for an absorbent body disposed on the back sheet 3 side of the absorbent core 7, and a core (not shown) for wrapping the absorbent core 7 and the nonwoven fabric sheet 8. In the present invention, the nonwoven fabric sheet may be disposed in the sheet of the core covering the absorbent core or may be disposed outside the core so as to be in contact with the core, but when the nonwoven fabric sheet is disposed in the sheet of the core covering the absorbent core, it is advantageous for liquid such as body fluid to be absorbed and diffused, and therefore, the nonwoven fabric sheet is preferably disposed in the sheet of the core covering the absorbent core. In the present specification, the term "absorbent body" refers to a structure in which an absorbent body including an absorbent core and a core wrap surrounding the absorbent core is disposed so as to be in contact with the absorbent core, or a structure in which the absorbent body is disposed so as to be in contact with the core wrap outside the core wrap. In the present invention, the nonwoven fabric sheet or a liquid-diffusing sheet different from the nonwoven fabric sheet may be disposed on the front sheet side of the absorbent core in order to further improve the diffusion of a liquid such as a body fluid passing through the front sheet.

The absorbent core is not particularly limited, and for example, an absorbent core in which a super absorbent polymer is dispersed and held in a fiber aggregate such as fluff pulp or nonwoven fabric can be used. The super absorbent polymer has a three-dimensional mesh structure in which a water-soluble polymer is appropriately crosslinked, and can absorb water 20 times or more its own weight. Examples of such super absorbent polymers include starch polymers, crosslinked carboxymethylated celluloses, acrylic acid polymers such as polymers or copolymers of acrylic acid or acrylic acid alkali metal salts, and amino acid polymers.

In the present invention, a nonwoven fabric sheet for an absorbent article is composed of 3 or more layers including a pulp fiber layer containing a pulp and having a first surface and a second surface, a first surface-side fiber layer disposed on the first surface side of the pulp fiber layer and mainly containing hydrophilic fibers having an average fiber length of 25mm to 64mm, and a second surface-side fiber layer disposed on the second surface side of the pulp fiber layer and mainly containing hydrophilic fibers having an average fiber length of 25mm to 64 mm.

In the present invention, "mainly comprising hydrophilic fibers" means a case where the hydrophilic fibers are contained at a ratio of more than 50 mass% with respect to the mass of the whole. In other words, the term refers to a case where the hydrophilic fiber is contained in an amount of more than 50 mass% and 100 mass% or less and the other component (for example, the hydrophobic fiber) is contained in an amount of 0 mass% or more and less than 50 mass%.

Fig. 4 is a cross-sectional view (schematic view) of a nonwoven fabric sheet according to an embodiment of the present invention. The nonwoven fabric sheet 8 of the present embodiment is composed of a 3-layer laminate, and the 3-layer laminate includes: a pulp fiber layer 81 having a first side and a second side; a first surface-side fiber layer 82 disposed on the first surface side of the pulp fiber layer 81; and a second face-side fiber layer 83 disposed on the second face side of the pulp fiber layer.

The pulp fiber layer of the present invention generally mainly contains a pulp (i.e., a pulp contained in a proportion of more than 50 mass%) which is a cellulose fiber having a fiber length of 1 to 10mm, and preferably consists of 100 mass% of the pulp. The kind of the pulp is not particularly limited, and any pulp such as wood pulp, non-wood pulp, old pulp, and the like can be used, but in view of high ability of liquid such as body fluid diffused in the first surface-side fiber layer and the second surface-side fiber layer to be taken up from the first surface-side fiber layer and the second surface-side fiber layer, fluff pulp is particularly preferably used.

The slurry is preferably a slurry containing a Kajani (Kajaani) having an average fiber length of 2 to 3mm, in terms of water absorption, water retentivity, flexibility, ease of handling, and the like. Note that the "kanani average fiber length" means that the fiber length of the paper pulp is measured in accordance with JAPAN TAPPI paper pulp test method No. 52: 2000, length weighted average fiber length measured by a fiber length measuring apparatus manufactured by Kaani Automation company. The basis weight (weight) of the slurry is not particularly limited, but is preferably 5 to 60g/m from the viewpoints of water retentivity, flexibility, volume (bulk), and the like ² About, more preferably 15 to 40g/m ² Left and right.

The first-surface-side fiber layer and the second-surface-side fiber layer of the present invention mainly contain hydrophilic fibers having an average fiber length of 25mm to 64mm (that is, contain the hydrophilic fibers at a ratio of more than 50 mass%), and preferably contain 70 mass% or more. The hydrophilic fiber is not particularly limited, but from the viewpoints of liquid diffusibility, strength, flexibility, versatility and the like, for example, a cellulose fiber and the like, and more specifically, a natural fiber such as cotton, a rayon, a regenerated fiber such as cuprammonium fiber and the like are exemplified. Further, synthetic fibers (rayon fibers and the like) having a hydrophilic surface may be used. Among them, rayon fiber is particularly preferably used from the viewpoints of liquid diffusibility, strength after interlacing, ease of handling, versatility, and the like.

In the present invention, the hydrophilic fiber preferably has an average fiber length in the range of 25mm to 64 mm. When the average fiber length is within this range, liquid such as discharged body fluid can be diffused widely and rapidly in the surface direction of the nonwoven fabric sheet by utilizing the capillary phenomenon of the fiber aggregate forming the first surface-side fiber layer and the second surface-side fiber layer, and the diffused liquid can be easily transferred to the pulp fiber layer disposed between the first surface-side fiber layer and the second surface-side fiber layer. The "average fiber length" is a fiber length according to JIS L1015: the average fiber length measured by the method "A7.1.1A method (standard method) for measuring the length of each fiber on a graduated glass plate" of the appendix a of 2010 "measurement of a7.1 fiber length". The above method corresponds to the test method of ISO 6989 published in 1981.

The form of the hydrophilic fiber is not particularly limited, and a general fiber having a circular cross section may be used, a fiber having an irregular cross section such as a Y-shape, a cross shape, or a hollow shape may be used, or a combination of these forms of fibers may be used. When the hydrophilic fiber includes a fiber having a modified cross section, the surface area of the fiber having a modified cross section is large and the liquid absorption property is excellent, and therefore, the liquid diffusibility of the fiber aggregate forming the first-surface-side fiber layer and the second-surface-side fiber layer can be further improved.

In the present invention, the first surface-side fiber layer and the second surface-side fiber layer may contain components other than the hydrophilic fibers at a smaller ratio (that is, at a ratio of less than 50 mass%) than the hydrophilic fibers, and preferably contain components other than the hydrophilic fibers at a ratio of 30 mass% or less. The other components include hydrophobic fibers, heat-bondable fibers, various treatment agents, fillers, and the like, and may be used alone or in combination as appropriate depending on the desired liquid diffusibility, strength, flexibility, water retentivity, production cost, and the like.

As the hydrophobic fiber, for example, a thermoplastic fiber such as polyethylene, polypropylene, nylon, or polyester, or a composite fiber obtained by combining these thermoplastic fibers, can be used, but from the viewpoint of strength, volume, and flexibility in wet conditions, a polyester fiber such as polyethylene terephthalate is preferably used.

In addition, from the viewpoint of liquid diffusibility and the like, the hydrophobic fibers are preferably fibers whose surfaces have been hydrophilically treated with a hydrophilic oil agent or the like, and more preferably polyester-based fibers having been hydrophilically treated. The hydrophilic oil agent used for the hydrophilic treatment is not particularly limited, and examples thereof include alkyl phosphate ester salts and alkyl phosphate metal salts. In the present invention, the first-surface-side fiber layer, the pulp fiber layer, and the second-surface-side fiber layer are integrated by a high-pressure water stream such as water jet as described later, and therefore, it is particularly preferable to perform hydrophilic treatment on the surface of the hydrophobic fiber by using a hydrophilic finish (durable hydrophilic finish) having durability to such an extent that the hydrophilic finish does not fall off by the high-pressure water stream. Examples of such durable hydrophilic oils include, but are not particularly limited to, oils obtained by mixing polyether esters, ether-type nonionic, polyether-modified silicon, sulfosuccinates, amide polyoxyethylene ethers, alkylimidazoline-type cations, polyglycerol polyesters, alkyl phosphate salts having 10 to 30 carbon atoms with betaine compounds having 10 to 30 carbon atoms, sulfate salts, and sulfonate salts, and oil mixtures of alkyl phosphate salts and polyether-modified silicon.

The heat-bondable fibers include those comprising a thermoplastic resin having a low melting point, such as a polyethylene resin or a low-melting polypropylene, at least on the surface thereof, and examples thereof include single-component fibers of a polyethylene resin; monocomponent fibers of polypropylene resin; a core-sheath composite synthetic fiber in which the core part is polyethylene terephthalate resin and the sheath part is polyethylene resin; a core-sheath composite synthetic fiber having a core part of polypropylene resin and a sheath part of polyethylene resin; a core-sheath composite synthetic fiber in which the core part is made of a high-melting polypropylene resin and the sheath part is made of a low-melting polypropylene resin; a bonding type (side by side) composite synthetic fiber composed of a polyethylene terephthalate resin and a polyethylene resin; and adhesive composite synthetic fibers made of polypropylene resin and polyethylene resin.

When the first surface-side fiber layer and the second surface-side fiber layer contain heat-bondable fibers, the first surface-side fiber layer, the pulp fiber layer, and the second surface-side fiber layer are integrated by a high-pressure water stream such as water jet to obtain a nonwoven fabric sheet, and then the nonwoven fabric sheet is subjected to heat treatment, whereby the low-melting-point resin of the heat-bondable fibers melts and is heat-bonded to other fibers, whereby the strength of the nonwoven fabric sheet, particularly the strength in wet state, can be improved. Since the thermally adhesive fibers are contained in a smaller amount by mass than the hydrophilic fibers, the thermally adhesive fibers do not inhibit the liquid diffusibility of the nonwoven fabric sheet and can contribute to the reinforcement of the strength of the nonwoven fabric sheet even if the thermally adhesive portion is formed.

The first surface-side fiber layer and the second surface-side fiber layer may be formed by an air-laid method or the like, but a carded web formed by a carding machine is preferably used as at least one of the first surface-side fiber layer and the second surface-side fiber layer. By using the carded web, even when the fiber length of the structural fibers is long, when the first surface side fiber layer, the pulp fiber layer, and the second surface side fiber layer are integrated by a high-pressure water stream such as water jet described later, the fibers in the respective fiber layers and the fibers between the respective fiber layers can be sufficiently entangled with each other. The form of the carded web is not particularly limited, and may be any form of a parallel web, a cross web, a random web, or the like.

In the present invention, the first-surface-side fiber layer and the second-surface-side fiber layer may be fiber layers having the same structure (i.e., fiber layers having the same type, mixing ratio, and layer structure of fibers), or may be fiber layers having different structures (i.e., fiber layers having at least 1 different type, mixing ratio, and layer structure of fibers).

Next, a method for producing a nonwoven fabric sheet for an absorbent article used in the absorbent article of the present invention will be described. The nonwoven fabric sheet can be obtained by a production method including at least: a step of supplying a web for the second-side fiber layer containing hydrophilic fibers; a step of supplying a slurry for a slurry fiber layer containing hydrophilic fibers onto the web; a step of supplying a web for a first surface-side fiber layer containing hydrophilic fibers onto the slurry to obtain a laminate; and a step of interlacing fibers between the fiber layers by applying high-pressure water flow treatment from both sides of the laminate. More specifically, the nonwoven sheet in which the first surface-side fiber layer, the pulp fiber layer, and the second surface-side fiber layer are integrated can be obtained by mixing the structural fibers such as the hydrophilic fibers as they are or at a predetermined mixing ratio, processing the mixture with a carding machine or the like to produce a web for the second surface-side fiber layer such as a carded web, then feeding a slurry for a pulp fiber layer containing hydrophilic fibers such as fluff pulp onto the web by air-laying or the like while transporting the produced web, further feeding a web for the first surface-side fiber layer containing hydrophilic fibers such as a carded web onto the slurry to obtain a laminate, and then performing high-pressure water treatment such as water jet from both surfaces of the laminate to interlace at least the fibers between the fiber layers with each other. In addition, when the first surface-side fiber layer and the second surface-side fiber layer contain heat-bondable fibers, the nonwoven fabric sheet obtained as described above is further subjected to heat treatment, whereby a nonwoven fabric sheet having enhanced sheet strength can be obtained.

The nonwoven fabric sheet obtained in this way has a structure in which the fibers in the respective fiber layers and the fibers between the respective fiber layers are entangled with each other by a high-pressure water flow such as a water jet, and therefore, the nonwoven fabric sheet has excellent sheet strength and liquid diffusibility, and can promote the transfer of liquid diffused in the surface direction of the nonwoven fabric sheet into the pulp fiber layer in the first surface-side fiber layer and the second surface-side fiber layer. In addition, since the first surface-side fiber layer and the second surface-side fiber layer after the liquid has been transferred to the pulp fiber layer can absorb the liquid again and diffuse the liquid in the planar direction, the cycle of the absorption of the liquid, the diffusion in the planar direction, and the transfer to the pulp fiber layer can be repeated in the nonwoven fabric sheet, and the diffusion region of the liquid and the amount of the liquid held by the nonwoven fabric sheet can be greatly increased by the continuous diffusion of the liquid.

Further, if the structure is provided in which a part of the structural fibers of at least one of the first surface-side fiber layer and the second surface-side fiber layer is caused to enter the inside of the pulp fiber layer by the high-pressure water flow such as the water jet, the liquid diffusing in the surface direction of the nonwoven fabric sheet is easily transferred to the pulp fiber layer in the first surface-side fiber layer and the second surface-side fiber layer, and therefore, the circulation of the absorption of the liquid, the diffusion in the surface direction, and the transfer to the pulp fiber layer in the nonwoven fabric sheet can be performed more quickly, and as a result, the diffusion rate and the diffusion region (diffusion area) of the liquid in the nonwoven fabric sheet can be further increased.

In the present invention, the liquid absorption height of the nonwoven fabric sheet for an absorbent article in a water absorption test by the Klemm (Klemm) method, which will be described later, is preferably 110mm or more, more preferably 120mm or more, and still more preferably 130mm or more. The water absorption capacity in the water absorption test of the nonwoven fabric sheet is preferably 2.0 times or more, more preferably 2.4 times or more, and still more preferably 3.0 times or more. When the liquid absorption height and the water absorption capacity are within the above ranges, it is possible to widely and rapidly diffuse a liquid such as a body fluid in the surface direction of the nonwoven fabric sheet, and to rapidly close the liquid inside the pulp fiber layer according to the liquid permeability height.

In the present invention, it is preferable that the liquid-absorbing height of at least one of the first surface-side fiber layer and the second surface-side fiber layer of the nonwoven fabric sheet is higher than the liquid-absorbing height of the pulp fiber layer. When the liquid-absorbing height in each fiber layer is in such a relationship, the first-surface-side fiber layer or the second-surface-side fiber layer easily transfers the liquid to a region where the liquid is not absorbed or retained in the pulp fiber layer in the above-described circulation, and therefore, the liquid can be diffused more continuously and more rapidly, and the liquid diffusion region and the water retention amount in the nonwoven fabric sheet can be further increased.

The water absorption test by the gram method can be performed in accordance with JIS P8141: the water absorption test method 2004 is used for the measurement, and the specific procedure thereof is described in the examples described later.

In the present invention, the nonwoven fabric sheet preferably has a thickness of 15 to 100g/m from the viewpoints of liquid diffusibility, sheet strength, liquid permeability and the like ² More preferably 20 to 80g/m ² Further preferably has a basis weight of 30 to 60g/m ² Basis weight of (c). The basis weight of each fiber layer constituting the nonwoven fabric sheet is determined from between the fibersThe pulp fiber layer is preferably 10 to 60g/m from the viewpoints of the state of formation of the interlaces, liquid diffusibility, sheet strength, liquid permeability, and the like ² In the right and left ranges, the first surface side fiber layer and the second surface side fiber layer are preferably 5 to 50g/m ² In the left and right ranges.

In addition, considering the formation state of capillaries required for the diffusion of liquid, the sheet strength, etc., the density of the nonwoven fabric sheet is preferably 50 to 300mg/cm ³ More preferably 50 to 200mg/cm ³ More preferably 60 to 150mg/cm ³ 。

In the present invention, the nonwoven fabric sheet may be used as a member that can be brought into contact with an absorbent body of an absorbent article, and for example, may be used as a diffusion sheet disposed on the front sheet side and/or the back sheet side of an absorbent core, a core wrap covering the absorbent core, or the like in the absorbent body. When the nonwoven fabric sheet is used for such a member, liquid such as discharged body fluid spreads widely in the nonwoven fabric sheet, and therefore, the liquid can be absorbed in a wide area of the absorbent core close to the nonwoven fabric sheet, and when the nonwoven fabric sheet is disposed on the back sheet side of the absorbent core, the rewet amount in the absorbent article can be significantly reduced (for example, by 20% or more).

The present invention can be applied to various absorbent articles such as an incontinence pad, a sanitary napkin, and a panty liner, in addition to the disposable diaper of the above embodiment. The absorbent article of the present invention is not limited to the above-described embodiments and the following examples, and can be modified as appropriate without departing from the object and spirit of the present invention.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not to be construed as being limited thereto.

Example 1

RAYON fibers (manufactured by daipabo RAYON co., ltd.) were prepared as hydrophilic fibers, polyethylene terephthalate (PET) fibers (manufactured by toyobo co., ltd.) whose surfaces were hydrophilically treated with a durable hydrophilic finish were prepared as hydrophobic fibers,the rayon fibers and the PET fibers were mixed so as to be 70% by mass/30% by mass, and then the basis weight was adjusted to 12.0g/m using a carding machine ² A carded web was made as the second face-side fibrous layer. The produced carded web was conveyed so that the basis weight became 21.0g/m ² The carded web was continuously supplied with a fluff pulp for a pulp fiber layer (NB 416, Weyerhaeuser) to form a pulp fiber layer on the second face side fiber layer. Next, a carded web produced in the same manner as the second surface-side fiber layer was supplied onto the pulp fiber layer to form a first surface-side fiber layer, and a laminate composed of the first surface-side fiber layer, the pulp fiber layer, and the second surface-side fiber layer was obtained. The laminate thus obtained was subjected to high-pressure water jet treatment by water jets (water pressure on the first surface side fiber layer side: 2 to 5MPa, water pressure on the second surface side fiber layer side: 3MPa, nozzle diameter: 92 μm, nozzle pitch: 0.5mm, 2 rows) from both surfaces of the laminate while being conveyed at a conveyance speed of 10 m/min, thereby interlacing the structural fibers in each fiber layer and between each fiber layer, and thus a 3-layer nonwoven fabric sheet in which the first surface side fiber layer, the pulp fiber layer, and the second surface side fiber layer were integrated was obtained.

Example 2

Except that the fluff pulp for the pulp fiber layer was made to be 26.0g/m in basis weight ² The production was carried out in the same manner as in example 1 except that the nonwoven fabric sheet was fed onto the carded web, thereby obtaining a 3-layer nonwoven fabric sheet.

Example 3

A nonwoven fabric sheet having a 3-layer structure was obtained in the same manner as in example 2, except that the carded webs forming the first-side fiber layer and the second-side fiber layer were not made of hydrophobic fibers (PET fibers).

Comparative example 1

RAYON fiber (DAIWABO RAYON co., ltd) was prepared as a hydrophilic fiber, and polyethylene terephthalate (PET) fiber (tokyo textile) whose surface was hydrophilically treated with a hydrophilic finish was preparedManufactured by kokai corporation), the rayon fibers and the PET fibers were mixed so as to be 30 mass%/70 mass% rayon fibers, and then a carding machine was used so that the basis weight was 22.5g/m ² A carded web was made as a fibrous layer corresponding to the second face-side fibrous layer of the present invention. While the produced carded web was conveyed, a carded web produced in the same manner as the fiber layer corresponding to the second surface side fiber layer was fed onto the carded web, and a fiber layer corresponding to the first surface side fiber layer of the present invention was formed, thereby obtaining a laminate composed of two fiber layers. The laminate thus obtained was subjected to high-pressure water jet treatment using water jets as in example 1 from both sides thereof while being conveyed at a conveyance speed of 10 m/min, thereby interlacing the structural fibers in the fiber layers and between the fiber layers, and a nonwoven fabric sheet having a two-layer structure in which the fiber layer corresponding to the first-surface-side fiber layer and the fiber layer corresponding to the second-surface-side fiber layer were integrated was obtained.

Comparative example 2

A nonwoven fabric sheet having a two-layer structure was produced in the same manner as in comparative example 1, except that the carded web forming each fiber layer was prepared by mixing rayon fibers/PET fibers at 30 mass%/70 mass%.

Comparative example 3

A nonwoven fabric sheet having a two-layer structure was produced in the same manner as in comparative example 1, except that the carded web forming each fiber layer was prepared by mixing rayon fibers/PET fibers at 70 mass%/30 mass%.

The basis weights (g/m) of the nonwoven fabric sheets of examples 1 to 3 and comparative examples 1 to 3 obtained as described above were measured by the measurement method described below ² ) Thickness (mm), density (g/cm) ³ ) The liquid absorption height (mm) after 5 minutes by the gram method, and the amount of the liquid to be transported per unit mass (g/g). Further, the rayon fiber and P in the first-side fiber layer and the second-side fiber layer were measured by the measurement method described later using each carded web produced in the process of producing the nonwoven fabric sheet described aboveET fiber mix ratio. The measurement results are shown in table 1.

[ Table 1]

As shown in table 1, the nonwoven fabric sheets of examples 1 to 3 all had a liquid absorption height of 120mm or more and a transport amount of 3g/g or more, exhibited extremely high liquid absorption height and transport amount as compared with the nonwoven fabric sheets of comparative examples 1 to 3, and had excellent liquid diffusibility. Further, as can be seen from comparison of examples 1 to 3, the higher the mixing ratio of the rayon fibers in the first surface-side fiber layer and the second surface-side fiber layer, the higher the liquid-absorbing height and the transport amount, and the liquid diffusibility of the nonwoven fabric sheet was increased in accordance with the mixing ratio of the rayon fibers.

The measurement method of each measurement item is as follows.

[ basis weight ]

10 specimens each having a size of 100mm × 100mm were selected and the mass of each specimen was measured. Next, the mass (g) of each sample was divided by the area (m) of each sample ² ) The basis weight (g/m) of each sample was calculated from the basis weight ² ). The basis weight of 10 specimens in total was calculated as an average value, and the average value was used as the basis weight.

[ thickness ]

The thickness of the nonwoven fabric was measured by using THICKNESS GAUGE UF-60 manufactured by Daorhizi Seiki Kaisha. In UF-60, the diameter of the measurement surface was 44mm, and the thickness was measured by applying a pressure of 0.3kPa to the nonwoven fabric.

[ Density ]

The density of the nonwoven fabric was calculated by dividing the basis weight of the nonwoven fabric by the thickness thereof.

[ liquid-suction height and amount of transportation ]

The liquid absorption height and the amount of liquid transferred after 5 minutes by the gram method were in accordance with JIS P8141 as follows: the water absorption test method 2004.

(1) The sample was cut into pieces of 230mm × 25mm (length × width), and the cut pieces were cut from the longitudinal directionA seal line was drawn out at a position of 30mm from the end of the test piece, and the initial mass (W) of the test piece was measured ₀ )。

(2) The artificial urine was filled into a rectangular parallelepiped dipping vessel of 170mm × 90mm × 40mm (length × width × depth) to a height of 35 mm. The artificial urine was prepared by dissolving 200g of urea, 80g of sodium chloride, 8g of magnesium sulfate, 3g of calcium chloride, and about 1g of a coloring agent in 10L of ion-exchanged water: blue No. 1.

(3) The test piece was fixed to the hanging tool so that the seal line was positioned on the lower side, immersed in artificial urine until reaching the seal line, and left to stand for 5 minutes.

(4) After leaving for 5 minutes, the height of the artificial urine rising from the seal line was measured as a liquid absorption height (mm).

(5) Next, the test piece was detached from the hanging tool, the portion of 30mm in length (portion below the seal line) immersed in artificial urine was cut, and the mass (W) of the remaining portion of 200mm in length was measured ₁ )。

(6) The conveying amount (X) (g/g) was calculated according to the following equation.

X＝{(W ₁ ×230/200)-W ₀ }/W ₀

(7) The above test was repeated 5 times, and the average value was used.

[ mixing ratio of rayon fiber to PET fiber ]

Regarding the mixing ratio of the rayon fibers and the PET fibers in the carded web, it was determined by measuring the mixing ratio of the rayon fibers in the following order.

(1) As a measurement sample, a fiber web containing rayon fibers and PET fibers was prepared.

(2) About 0.2g of the web was cut into a size of about 100mL in a beaker, and the mass (g) of the cut web (sample initial mass W) was measured _A )。

(3) The cut web and 30g of hexafluoroisopropanol were put in a 100mL beaker and stirred at 300rpm for 1 hour.

(4) The mass (g) (initial mass W of filter paper) measured in advance was used _F ) To the inside of the beakerThe contents were filtered.

(5) The residue on the filter paper was placed in a ventilation chamber for each filter paper, and dried for 1 hour.

(6) The mass (g) of the residue and the filter paper after drying was measured.

(7) Starting from the initial mass W of the sample _A Initial mass W of filter paper _F In the total amount of (a), the mass (g) of the rayon fiber in the fiber web (the mass W of the rayon fiber) is calculated by removing the mass of the residue after drying and the mass of the filter paper _R )。

(8) According to the calculated mass of the rayon fiber and the initial mass W of the sample _A The mixing ratio F of the rayon fibers was calculated according to the following formula _A (mass%).

F _A ＝(W _R /W _A )×100

Hereinafter, the assumed embodiment of the present invention will be described by way of example.

One aspect (aspect 1) of the present invention relates to an absorbent article including a liquid-permeable front sheet, a liquid-impermeable back sheet, an absorbent body positioned between the front sheet and the back sheet, and a nonwoven fabric sheet for the absorbent body, wherein the nonwoven fabric sheet includes: a pulp fiber layer comprising pulp and having a first face and a second face; a first surface-side fiber layer which is disposed on the first surface side of the pulp fiber layer and mainly contains hydrophilic fibers having an average fiber length of 25mm to 64 mm; and a second surface-side fiber layer which is disposed on the second surface side of the pulp fiber layer and mainly comprises hydrophilic fibers having an average fiber length of 25mm to 64 mm.

In another aspect (aspect 2) of the present invention, in the absorbent article according to aspect 1, at least one of the first surface-side fiber layer and the second surface-side fiber layer further includes a hydrophobic fiber in a smaller amount by mass than the hydrophilic fiber.

In another aspect (aspect 3) of the present invention, the absorbent article according to aspect 2 is based on, wherein the hydrophobic fibers include thermoplastic fibers.

In another aspect (aspect 4) of the present invention, the absorbent article according to aspect 3 is based on, wherein the thermoplastic fibers are polyester fibers subjected to hydrophilic treatment.

In another aspect (aspect 5) of the present invention, in the absorbent article according to any one of aspects 1 to 4, the hydrophilic fibers of the fiber layer on at least one of the first surface-side fiber layer and the second surface-side fiber layer have a modified cross section.

In another aspect (aspect 6) of the present invention, in the absorbent article according to any one of aspects 1 to 5, the hydrophilic fibers of the fiber layer on at least one of the first surface-side fiber layer and the second surface-side fiber layer include cellulose-based fibers.

In another aspect (aspect 7) of the present invention, in the absorbent article according to any one of aspects 1 to 6, the slurry of the slurry fiber layer includes fluff pulp.

In another aspect (aspect 8) of the present invention, the absorbent article according to any one of aspects 1 to 7, wherein the pulp of the pulp fiber layer contains pulp having a kappa average fiber length of 2 to 3 mm.

In another aspect (aspect 9) of the present invention, there is provided an absorbent article according to any one of aspects 1 to 8, wherein the absorbent article has a structure in which fibers between fiber layers are entangled with each other by an action of water flow.

In another aspect (aspect 10) of the present invention, based on the absorbent article according to any one of aspects 1 to 9, at least one of the first surface-side fiber layer and the second surface-side fiber layer includes a carded web.

In another aspect (aspect 11) of the present invention, in the absorbent article according to any one of aspects 1 to 10, the absorbent article includes a structure in which a part of fibers of the fiber layer of at least one of the first surface-side fiber layer and the second surface-side fiber layer penetrates into the inside of the pulp fiber layer.

In another aspect (aspect 12) of the present invention, in the absorbent article according to any one of aspects 1 to 11, a liquid-absorbent height of at least one of the first surface-side fiber layer and the second surface-side fiber layer is higher than a liquid-absorbent height of the pulp fiber layer in a water absorption test by the klemm method.

In another aspect (aspect 13) of the present invention, in the absorbent article according to any one of aspects 1 to 12, the absorbent body includes an absorbent core, and the nonwoven fabric sheet is disposed at least between the back sheet and the absorbent core.

Another aspect (aspect 14) of the present invention relates to a method for manufacturing a nonwoven fabric sheet for an absorbent used in an absorbent article according to any one of aspects 1 to 13, including: a step of supplying a web for the second-side fiber layer containing hydrophilic fibers; a step of supplying a slurry for a slurry fiber layer containing hydrophilic fibers onto the web; a step of supplying a web for a first surface-side fiber layer containing hydrophilic fibers onto the slurry to obtain a laminate; and a step of performing high-pressure water stream treatment from both sides of the laminate to interlace at least fibers between the fiber layers.

Description of the symbols

Disposable diaper 1

2 surface sheet

3 Back sheet

4 absorbent body

5 cover sheet

61-64 elastic member

7 absorbent core

8 non-woven fabric sheet

Claims

1. An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, an absorbent body positioned between the top sheet and the back sheet, and a nonwoven fabric sheet for the absorbent body, wherein,

the nonwoven fabric sheet includes:

a pulp fiber layer comprising pulp and having a first face and a second face;

a first surface-side fiber layer which is arranged on the first surface side of the pulp fiber layer and mainly comprises hydrophilic fibers having an average fiber length of 25mm to 64 mm; and

and a second-side fiber layer which is disposed on the second surface side of the pulp fiber layer and mainly comprises hydrophilic fibers having an average fiber length of 25mm to 64 mm.

2. The absorbent article of claim 1,

at least one of the first surface-side fiber layer and the second surface-side fiber layer further includes a smaller amount of hydrophobic fibers than hydrophilic fibers in terms of mass ratio.

3. The absorbent article of claim 2, wherein,

the hydrophobic fibers comprise thermoplastic fibers.

4. The absorbent article according to claim 3,

the thermoplastic fiber is a polyester fiber after hydrophilic treatment.

5. The absorbent article according to claim 1 or 2, wherein,

the hydrophilic fibers of at least one of the first surface-side fiber layer and the second surface-side fiber layer have a modified cross section.

6. The absorbent article according to claim 1 or 2, wherein,

the hydrophilic fiber of at least one of the first surface-side fiber layer and the second surface-side fiber layer comprises a cellulose fiber.

7. The absorbent article according to claim 1 or 2, wherein,

the slurry of the slurry fiber layer comprises fluff pulp.

8. The absorbent article according to claim 1 or 2, wherein,

the size of the size fiber layer comprises size with the average fiber length of 2-3 mm of Kayni.

9. The absorbent article according to claim 1 or 2, wherein,

the absorbent article includes a structure in which fibers between respective fiber layers are interlaced with each other by the action of water flow.

10. The absorbent article according to claim 1 or 2, wherein,

at least one of the first surface-side fiber layer and the second surface-side fiber layer includes a carded web.

11. The absorbent article according to claim 1 or 2, wherein,

the absorbent article includes a structure in which a part of fibers of the fiber layer of at least one of the first surface-side fiber layer and the second surface-side fiber layer enters the inside of the pulp fiber layer.

12. The absorbent article according to claim 1 or 2, wherein,

in the water absorption test by the kreb method, the liquid absorption height of at least one of the first surface-side fiber layer and the second surface-side fiber layer is higher than the liquid absorption height of the pulp fiber layer.

13. The absorbent article according to claim 1 or 2, wherein,

the absorbent body includes an absorbent core, and the nonwoven fabric sheet is disposed at least between the back sheet and the absorbent core.

14. A method for producing a nonwoven fabric sheet for use in an absorbent article according to any one of claims 1 to 13, the method comprising:

a step of supplying a web for the second-side fiber layer containing hydrophilic fibers;

a step of supplying a slurry for a slurry fiber layer containing hydrophilic fibers onto the fiber web;

a step of supplying a web for a first surface-side fiber layer containing hydrophilic fibers onto the slurry to obtain a laminate; and

and a step of performing high-pressure water stream treatment from both sides of the laminate to interlace at least fibers between the fiber layers.